One of the possible services in the fan and blower industry is to design and manufacture custom fan tray systems. The manufacturing of custom fan tray systems involves sheet metal manufacturing and assembly work. The dimensions to rounded edges (bends) of sheet metal parts are given to the theoretical sharp corners. The location of the theoretical sharp corner is also referred to as mold lines or apexes, and is defined as the location in space where two walls would intersect if they joined at a sharp corner rather than at a rounded edge. Despite the sophisticated equipment available for the manufacture of custom fan trays, there is no adequate handheld tool to measure the lengths of sheet metal walls that are not bent at a right angle. The lengths are most commonly measured to the corner where two walls meet. The corner of two walls that do not meet at right angles is commonly referred to as a “theoretical sharp corner”. Typically during first article inspections the measurement of these walls are skipped since there is no method to easily measure walls with theoretical sharp corners.
When a sheet metal design having a theoretical sharp corner is given to a brake press operator for a forming operation, the operator either estimates the length of the wall, or a “custom go/no go” gage is built to check the length. Such gages do not specifically measure values; rather, they merely indicate to the operator whether the part is acceptable. Custom gages have to be designed and built for each application, and can be quite expensive. Moreover, such gages are only useful for one application.
In order to solve this measurement problem it has been envisioned to use combination squares to indirectly measure the length of walls with theoretical sharp corners. However, indirect measurement using a combination square can be slow and cumbersome, can rely heavily on operator technique, and can be very inaccurate. It has also been envisioned to use more sophisticated measuring equipment for measuring theoretical sharp corners such as coordinate measuring machines, video capture systems, and optical comparators. However, these are complex, specialized equipment and tend to be quite expensive as compared to a hand held device such as, for example, slide calipers. Such equipment would tend to be maintained in a fixed location such as a quality lab, and therefore those wanting to use the equipment on a shop floor or in design engineering offices would not have timely access to such equipment. Moreover, the sophisticated metrology equipment would require specialized training and dedicated operators.
Accordingly, it is an object of the present invention to provide a simple, hand-held and inexpensive apparatus for accurately measuring the length of structures between one or more theoretical sharp corners that overcomes the above-mentioned drawbacks and disadvantages.